Portable, free standing, shelters that have a collapsible frame structure that supports a canopy are well known. Portable shelters typically employ a cloth or plastic canopy attached to a light-weight, highly foldable skeleton or frame structure. The canopy provides a roof and/or walls for the shelter, and the frame structure provides support for the canopy, for example, the frame structure includes legs to elevate the roof and a system of trusses to support the roof and to generally stabilize the shelter. The frame structure often incorporates a compound, scissor-like, arrangement of a light-weight, tubular material such as aluminum. In order to maximize the usable area under a shelter, the frame structure is often designed so that the roof is supported solely by legs positioned near the perimeter of the roof. Stated alternatively, shelters do not typically employ an interior supporting post or leg such as a leg or post positioned in the center of shelter. An example of such a portable shelter is provided in U.S. Pat. No. 4,641,676 to Lynch the contents of which are herein incorporated in their entirety by reference.
To further maximize the usable area under the canopy, several portable shelter designs have incorporated eaves or awning-like structures that support the canopy beyond the exterior boundary or envelope defined by the legs of the shelter's frame. For example, U.S. Pat. No. 6,718,995 to Dotterweich describes a portable shelter having a canopy extension that extends out from one side of the shelter. The extension is supported by a relatively complex secondary network of trusses and cross-supports independent from that of the main body of the shelter. This single canopy extension design has the disadvantage of increasing the weight and size of the collapsed shelter, decreasing the effective height of the shelter along the outer boundary of the canopy extension, and being susceptible to deformation and damage from environmental forces, such as wind, due to the relatively large, unsupported extension.
U.S. Pat. No. 7,367,348 to Tsai et al., the contents of which are herein incorporated in their entirety by reference, describes a portable shelter having a canopy extension extending from four sides of the shelter. The canopy extension is supported by the end portions of certain of the trusses that support the canopy roof. The end portions supporting the canopy extension are entirely unsupported by secondary trusses or struts. This canopy extension design is also relatively susceptible to deformation and damage from environmental forces, such as wind, due to the unsupported nature of the canopy extension.
U.S. Publication No. 2007/0186967 to Zingerle, the contents of which are herein incorporated in their entirety by reference, describes a canopy extension that is supported by primary struts extending from the exterior corner of each support post. The primary strut is supported by one or more support strut that span between the primary strut and a network of side trusses. This canopy extension design has the disadvantage that a relatively large angle is formed between the support strut and the network of side trusses which, in turn, results in less fluid movement of the shelter frame when expanding and collapsing the shelter and increases the likelihood that the support strut will bind and/or kink. Furthermore, the fact that the primary struts extend from the corners of the support posts undesirably increases the collapsed size of the shelter.
Chinese Patent Application No. 2009201183292 to Kuanjun, the contents of which are herein incorporated in their entirety by reference, describes a canopy extension that is supported by primary struts extending from the exterior corners of each support post. The primary struts are supported by a support strut that is attached to the primary strut at one end and slidibly attached to the exterior corner of the support post at an opposite end. This canopy extension design has the disadvantages that the strut support is not limited in its upward movement on the support post. In the event that an environmental force, such as wind, acts against the support strut, the support strut will be prone to upward movement which, in turn, causes deformation and damage to the canopy extension and frame generally. Furthermore, the fact that the primary struts and support struts extend from the corners of the support posts undesirably increases the collapsed size of the shelter.
What is needed in the art is a shelter design that maximizes the area shaded and protected by the deployed shelter and that does so without sacrificing the stability and strength of the shelter, complicating the operation of the shelter, or increasing the weight, collapsed size or storability, or cost of the shelter.